This invention relates in general to conveyor systems and, in particular, to a heavy duty conveyor system such as used as an elevator in earth moving equipment, such as a carry-type scraper, where the elevator is used to move dirt within the scraper bowl.
More specifically, but without restriction to the particular use which is shown and described, this invention relates to a mounting for a conveyor drive roller to control tracking of the conveyor as it passes over and about the supporting rollers.
Control of the path of travel, or tracking, of a conveyor is necessary to prevent the endless belt or web from tracking off the drive or idler rollers, or causing the conveyor web or belt to break. As a conveyor belt moves about the supporting roller in its endless path of movement, lateral force is applied to the conveyor belt causing the belt to creep or travel laterally upon the rollers. This lateral movement of the conveyor belt upon the supporting rollers eventually will cause the belt to track off the rollers or create a lateral force sufficient to cause the belt to rupture. Such lateral force is caused by the non-parallel alignment of the supporting rollers which may occur through the accumulation of manufacturing tolerance errors, or may be the result of damage to the supporting rollers or conveyor frame through operations in the field. Such misalignment is especially troublesome in earth moving equipment where the conveyors carry heavy loads and are frequently subjected to heavy impact from the materials being loaded into the scraper bowl. Due to these unusual problems encountered when using a conveyor in earth moving equipment such as scrapers, the conveyor rollers are frequently misaligned.
Scrapers generally include a box-type structure, referred to as a "bowl", open at its forward end with the bottom or floor of the bowl having an adjustable forward cutting edge adapted to cut a predetermined amount from the upper surface of the ground. The bowl is normally open at its forward end so that the material cut by the cutting edge as it moves through the ground will pass into the rear portion of the bowl. However, as the material is cut it accumulates adjacent to the cutting edge and does not spread uniformly throughout the scraper bowl. Therefore, an elevator or flight-type conveyor must be carried within the bowl and positioned to the rear of the cutting edge to receive the material as it is passed into the forward portion of the bowl to move it both rearwardly and upwardly for more even distribution.
These elevators generally comprise a pair of rigidly joined side frame members extending the full length of the elevator and carrying sprockets at the lower forward and upper rear ends which engage chains of a flight-type conveyor. Such elevators are normally provided with a mounting structure which permits floating action of the elevator over dirt or material entering the bowl to prevent damage to the elevator or cutting edge when a large stone or other object is hit by the scraper. However, while such structure prevents damage by permitting the elevator to float when a large stone is hit, these stones and the like passing into the bowl frequently damage the elevator throwing the conveyor rollers out of alignment.
Even if the equipment were initially properly aligned, in operation such misalignment frequently results in equipment failure and costly down time of the machine in the field. The present invention eliminates these problems by mounting the elevator drive roller to permit alignment with the idler roller so that the conveyor chain will track correctly on the elevator idler rollers and spools. While this invention is believed to have general applications to all types of conveyor systems for convenience of illustration, a preferred embodiment will be described with reference to its use in the elevator of a scraper.